or caterpillars of some moths are called cutworms (Agrotis,
Amathes, Peridroma, Prodenia spp.) because
of the manner in which they cut down young plants as they feed.
The adults are night-flying moths which feed on nectar, if at all,
and do no damage.
There are a
great many species of cutworms. While they all feed on plants by
chewing, they vary as to damage done and host plants preferred.
Generally they destroy more of the plant than they eat. Their numbers
vary greatly from year to year and, when numerous, may destroy as
much as 75% of a crop. Cutworms injure plants in four major ways:
surface cutworms cut off young plants at or slightly above or below
the soil line, sometimes dropping the severed plants into their
burrows. Because most of the plant is not eaten, these cutworms
do great damage, attacking and felling new plants nightly. The black,
bronzed, clay-backed and dingy cutworms are in this group.
species, usually the variegated and spotted cutworms, climb the
stem of trees, shrubs, vines, and crops and eat the leaves, buds
species, particularly the pale western and glassy cutworms, remain
in the soil and feed upon roots and underground parts.
- Army cutworms
occur in great numbers, consuming the tops of plants and then "marching"
on to other fields.
The many species
of cutworms can be quite distinct. Many are stout, smooth, soft-bodied,
plump caterpillars. These vary from brown or tan to pink, green
or gray and black. Some are all one color, others spotted or striped.
Some larvae are dull, others appear glassy. The adults are generally
very robust brown or black moths showing various splotches, blotches
or stripes in shades of gray, brown, black or white.
cutworm and damaged stalk
(Clemson University Extension)
pass the winter as partially grown larvae. Thus they are already
large, voracious feeders when transplants and seedlings are set
out in the fields. A few species pass the winter as pupae or hibernating
moths. Overwintering cutworms may live under trash or bark, in clumps
of grass or in earthen cells in the soil. These cutworms become
active and begin feeding as the weather warms in spring, remaining
hidden under debris or in the soil and feeding at night. Many species
continue to feed well through June, then pupate in the soil to emerge
later as moths. Normally there is only one generation per year.
The moths crawl from their brown pupal cases in the soil and climb
up through the soil, following the tunnel made by the burrowing
larva. If this tunnel is blocked, the fragile moth cannot escape
the soil. Cutworm abundance and development is greatly affected
by weather, especially rainfall. The moths mate and lay eggs in
late summer, beginning the next generation. The moths often seek
out grassy or weedy areas to lay their eggs, which are usually deposited
on plant stems or in the soil. One female may lay hundreds of eggs.
The hatching larvae feed until cold weather and then hide for the
winter in a sheltered, dry place.
practices may offer some degree of control:
- Plow and
fallow fields in mid- to late summer to prevent the laying of eggs.
- Plow in the
fall to expose the larvae or deeply bury the pupae.
fields in the spring after vegetation has appeared and grown a few
inches, then delay seeding to starve the cutworms.
- Plan rotations
to avoid row or hill crops following a grassy sod. Plow sod fields
in late summer or early fall the year before planting.
frequently to injure and expose hiding cutworms to predators.
- The construction
of ditches and dusty furrows may interrupt armyworms.
- Place foil
or paper wraps or cardboard collars around transplants; extend a
few inches into the soil and several inches up the stem.
- Dig in the
soil around damaged or adjacent plants in the row; find and destroy
- Plant a thick
"trap crop" of sunflower, a favored host, around the perimeter of
the garden; find and destroy attacking cutworms daily.
- Use a tanglefoot
band on trees being attacked by climbing cutworms.
- Other suggested
home remedies include catching and placing toads in the garden,
wrapping onion stems around the stems of transplants, placing a
ring of moist wood ashes around the plants, and placing a toothpick
or 16d nail alongside each transplant stem. Chemical treatments
are available as either homemade or commercial poison baits or as
insecticide treatments directed to the soil surface or on and around
the plants. Granular insecticide treatments, applied to protect
the seed and developing seedlings from soil insects, are of little,
if any, value in controlling cutworms.
from G.R Nielsen, University of Vermont Extension, 1999